ROGERS, GEOLOGY OF THE CORTLANDT SERIES 



59 



they all belong to the same series. The norites occupy a central position 

 in the area, being flanked by diorite and pyroxenite, and often, at least, 

 protected on the north and south by more acid rocks. The biotite augite 

 norite magma is the largest and is closely connected with the norite proper 

 and the biotite norite ; while the hornblende norite shows closer affinities 

 with the diorites. The pyroxenites comprise the eastern third of the 

 series, and possibly likewise extend to the west, since they are found on 



BC DEFG HI 



K 



40 



45 SO 55" 60 65 70 



Fig. 3. Variation Diagram of the Cortlandt Series 



A = Diorite; B = Hornblende Norite; C = Biotite Norite; D = Olivine 

 Pyroxenite ; E = Pyroxenite ; F = Biotite Augite Norite ; G = Norite ; H = 

 Gabbro; I = Augite Norite; K = Granite. (The rocks of tbe New Jersey and 

 Connecticut extensions of the series are not included.) 



Montrose Point and again across the river, on Stony Point. They be- 

 come chrysolitic in apparently irregular patches. Finally, the diorites 

 occupy an area to the west which contains most of the inclusions of the 

 district; and in several places where there is reason to believe that inclu- 

 sions have existed but have been absorbed, diorite is also found. Gabbro 

 is found in two cases next to the limestone, and in two others adjoining 

 schist, while syenite is in an analogous location. 



The problem suggested by the location of these last rocks is a difficult 

 one to solve. According to Harker, 45 the hybrid formed by the absorption 



46 Jour. Geol., VIII, 380-399. 1900. Also Nat. Hist, of Ign. Rocks, Chap. XIV. 1909. 



